Iowa Geological Survey, Guidebook 25. Living Karst
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LIVING IN KARST Iowa Geological Survey Guidebook Series No. 25 IOWA FIELD CONFERENCE FOR PUBLIC POLICY MAKERS OCTOBER 11-12, 2005 Iowa Department of Natural Resources Jeffrey R. Vonk, Director October 2005 COVER The collapse of rock and soil into underground crevices and caves causes sinkholes (circular pits) in regions of shallow limestone. Aerial photo over Clayton County by Gary Hightshoe, Iowa State University Printed in-house on recycled paper. LIVING IN KARST Iowa Geological Survey Guidebook Series No. 25 IOWA FIELD CONFERENCE FOR PUBLIC POLICY MAKERS OCTOBER 11-12, 2005 Edited by Robert D. Libra With contributions by Paul Berland Bob Libra Northeast Iowa RC & D Iowa DNR-Geological Survey Bruce Blair Jeff Myrom Iowa DNR-Forestry Iowa DNR-Solid Waste Michael Bounk Eric O'Brien Iowa DNR-Geological Survey Iowa DNR-Water Monitoring Lora Friest Karen Osterkamp Northeast Iowa RC & D Iowa DNR-Fisheries Scott Gritters Dave Pahlas Iowa DNR-Fisheries City of Decorah Cathy Henry John Pearson U.S. Fish and Wildlife Service Iowa DNR-Parks & Recreation John Hogeman James Ranum Winneshiek County Landfill Nat. Res. Cons. Service Bill Kalishek LuAnn Rolling Iowa DNR-Fisheries Nat. Res. Cons. Service Chad Kehrli Joe Sanfilippo Iowa DNR-Field Office #1 Iowa DNR-Field Office #1 Rick Langel Mary Skopec Iowa DNR-Water Monitoring Iowa DNR-Water Monitoring Mike Wade Iowa DNR-Field Office #1 Iowa Department of Natural Resources Jeffrey R. Vonk, Director October 2005 95 TABLE OF CONTENTS ACKNOWLEDGEMENTS .............v INTRODUCTION ................1 STOP 1. Phelps Park – The Northeast Iowa Landscape and Water Quality . 5 STOP 2. Dunning Spring Park – Karst, Water Quality, and Economics . 9 STOP 3. Skyline Quarry – The View from Inside an Aquifer .....13 STOP 4. Decorah Hatchery – Trout Production and Water Quality ....15 STOP 5. Winneshiek County Landfill – Solid Waste in Karst ......17 STOP 6. Hecker Creek – Losing Streams ..........21 STOP 7. Postville Industrial Wastewater Treatment Plant – Wastewater and Water Quality ................25 STOP 8. Glenwood Cave – Caves in Iowa ..........27 STOP 9. Enyart Farm – AFOs in Karst Part 1 .........29 STOP 10. Forestry Planting – Alternative Land Use........33 STOP 11. Thompson-Reisinger Farm – AFOs in Karst Part 2 .....35 STOP 12. Rossville County Park – Stepping Inside a Sinkhole .....37 STOP 13. Lower Yellow River – Watersheds and Water Quality . 41 STOP 14. Effigy Mounds – Northeast Iowa and the Mississippi River . 47 97 ACKNOWLEDGEMENTS Many people assisted in the preparation of the field conference and guidebook. Those listed herein without affiliation are Iowa DNR staff. Contributors providing written work are listed on the title page. In particular, Joe Sanfilippo, Bill Kalishek, Lora Friest (NE IA RC&D), Luann Rolling (NRCS-Allamakee County), John Pearson, and Bruce Blair provided significant input to the trip design and details. In addition, Paul Van Dorpe organized the logistics for the trip. Jim Janette (Allamakee County Conservation Board) Gary Shawver (Shawver Well Com- pany), and Gene Tinker provided expertise at trip stops. Ray Anderson and Adam Kiel (NEIA RC&D), and in particular Calvin Wolter prepared many of the illustrations. Pat Lohmann formatted the guidebook and provided expertise on the graphics and design. Lois Bair, Chad Fields, Chris Kahle, Eric O’Brien, Lynette Seigley, and Calvin Wolter served as reviewers for the guidebook. Sharon Tahtinen, Mary Pat Heitman, Lois Bair, Karyn Stone, Lisa Ogle, and Tammie Krausman provided administrative support. Wayne Gieselman and Jeff Vonk provided management support. Finally, we acknowledge the numerous landowners who provided access to their property, and to the field conference participants. 99v Areas in the state with varying levels of karst development and potential. Figure 1. Figure 100vi INTRODUCTION The Karst Landscape of Northeast Iowa Bob Libra, State Geologist, Iowa Department of Natural Resources (DNR)-Geological Survey A variety of geologic factors have produced the karst, shallow rock, high relief landscape of northeast Iowa. First, Paleozoic age carbonate (limestone and dolomite) rocks form the uppermost bedrock over much of the area. These carbonate strata are broken into various sized “blocks” by vertical fractures and roughly horizontal bedding planes. As groundwater circulates through these cracks, it slowly dissolves the rock away, creating wide fractures, pipes, voids, and caves. Second, erosion has removed much of the glacial deposits that once covered the landscape, leaving the carbonate rocks near the surface, typically within 25 feet, and often within 10 feet. When rock that contains voids and openings is combined with a thin cover of soil, the soil may collapse into the rock openings, producing sinkholes. Finally, the proximity of this area to the deeply-cut Mississippi River Valley has resulted in steep, deep stream valleys. These solutionally modified karst-carbonate rocks are excellent aquifers. They are capable of transmitting large quantities of groundwater at quite fast rates. However, the presence of sinkholes allows surface runoff and any associated contamination to directly enter these rock strata. When sinkholes or enlarged fractures occur in stream valleys and other drainage ways, entire streams may disappear into the rock. These streams are called “losing streams.” In addition, “between the sinkholes,” the thin soil cover provides much less filtration of percolating water than occurs elsewhere in the state. These factors make the aquifers, and water wells tapping them, very vulnerable to contamination, and allow any contaminants that reach the aquifer to spread long distances very quickly – especially by groundwater standards. Water – and any contaminants – enter karst-carbonate aquifers via sinkholes, losing streams, and by infiltration through the shallow soils in flat upland areas. The water travels through cracks and voids to the water table, below which all voids are water-filled. The groundwater then travels “down-flow” through the broken rocks to springs and seeps along the deeply cut stream valleys. These springs and seeps supply much of the stream flow in shallow rock areas. The carbonate aquifers are underlain by less transmissive rocks, called confining beds, which act as the “bottom seal” of the aquifer. Springs and seeps are most prominent where the contact between the aquifer and the underlying confining bed is exposed in valleys. Karst conditions affect other parts of the state. Figure 1 shows areas in the state with varying levels of karst development and potential. However, the most visibly developed karst occurs in northeast Iowa. Figure 2 is a generalized stratigraphic column for northeast Iowa, showing the sequence of rocks that underlie the area. Figure 3 is a generalized geologic map showing where the various rock units form the uppermost rock. The unit called the Galena Limestone is the most karst-affected unit. In particular, most of the sinkholes and large springs in this area are formed in this unit. The unit called the Prairie du Chien Dolomite is another carbonate unit that exhibits voids and dissolved fractures, but few sinkholes. We will be referring to the rock column and geologic map throughout the trip to keep ourselves geographically and geologically located. 1 Legend shale limestone dolomite sandstone river sediments (mostly sand) brecciated cherty glauconitic Figure 2. Generalized stratigraphic column of northeast Iowa. 2 Figure 3. Generalized geologic map of northeast Iowa showing field conference stops. 3 Table 1-1. Algific slope snails and plants. Common Name Scientific Name State Status1 Federal Status2 SNAILS Iowa Pleistocene Snail Discus macclintocki Endangered Endangered Frigid Ambersnail Catinella gelida Endangered Minnesota Pleistocene Ambersnail Novisuccinea sp. A Endangered Iowa Pleistocene Ambersnail Novisuccinea sp. B Endangered Briarton Pleistocene Vertigo Vertigo briarensis Endangered Midwest Pleistocene Vertigo Vertigo hubrichti Threatened Bluff Vertigo Vertigo meramecensis Threatened Occult Vertigo Vertigo occulta Threatened Iowa Pleistocene Vertigo Vertigo new species Threatened PLANTS Balsam Fir Abies balsamea Special Concern Northern Wild Monkshood Aconitum novaboracense Threatened Threatened Moschatel Adoxa moschatellina Special Concern Golden Saxifrage Chrysosplenium iowense Threatened Bunchberry Cornus canadensis Threatened Limestone Oak Fern Gymnocarpium robertianum Special Concern Northern Lungwort Mertensia paniculata Endangered Bog Bluegrass Poa paludigena Special Concern Northern Currant Ribes hudsonianum Threatened Prickly Rose Rosa acicularis Endangered Rosy Twisted-stalk Streptopus roseus Threatened 1) State status definitions. Endangered: likely to become extinct in state, protected by state law; Threatened: likely to become Endangered in state, protected by state law; Special Concern: in need of study of distribution and status in state, not protected by state law. 2) Federal status definitions. Endangered: likely to become extinct in all or a significant portion of its total range. Threatened: likely to become Endangered in all or a significant portion of its total range. Threatened and Endangered plants are protected by federal law on federal lands; Threatened and Endangered animals are protected by federal law throughout their national range. 4 STOP 1. Phelps Park – The Northeast Iowa Landscape and Water Quality Geologic Setting Our first stop, Phelps Park, overlooks the Upper Iowa River Valley from a cliff-like hillside